Elevator installations for transport of persons/goods are relatively long-term capital assets with service lives of 20 years and more. If after a time of such length a general overhaul of an elevator installation occurs, then the components of the elevator installation are often aged in terms of technology, which obliges a more or less complete exchange of the components, termed modernization in the following.
It is disadvantageous with this method of modernization of an elevator installation that the transport capacity of the elevator installation during the modernization is at best maintained. If in an elevator installation with, for example, three elevators an elevator is exchanged then this means a temporary reduction in transport capacity by 33%. The users, thereagainst, do not want to suffer any losses in convenience during the modernization and in addition want to be transported as quickly and directly as possible. Long waiting times or inconvenient transfers are regarded as unacceptable.